Bottlehead Forum
Bottlehead Kits => Kaiju Stereo 300B amp => Topic started by: currly30 on July 29, 2022, 12:17:46 AM
-
Looking at getting the Kaiju to run my near field speaker set up on ~87db speakers. My desk is currently set up in one corner of the room. To give a ruff measurements: The fronts of the speakers would be about 6' away from a wall. The backs would be about 30' from a wall. Left side about 5' and right side about 25'. Also the ceiling is 9' high above the desk then take a sharp incline to 14'. Basically I'm wondering if, in my very unique room situation, the kaiju would be enough for near field use. I am currently using a 75watt SMSL amp and it gets plenty loud. I have it set at about half volume then use my pre-amp to fine control the volume.
-
Also, a second question. Is it possible to use 2a3 tubes in the Kaiju? Or would it require rewiring the Kaiju?
-
For desktop use, the Kaiju would definitely be plenty of power. We have had many customers in the past use our 2W SEX amp with 87dB desktop speakers for this use. If your speakers are 8 ohms, you can get out your multimeter and set it to AC volts, then open up a tone generator app and play a 60Hz tone through your speakers until you see 8V on your meter. That would represent 8W and the Kaiju still has some dynamic headroom beyond that.
The Kaiju is not at all optimized for 2A3 tubes and you would have to replace the power transformer and redesign the circuit to make that work, at which point you'd end up pretty close to a Stereomour.
-
Thank you the info. I will have to try out putting 8w through my speakers to see how loud they get.
-
They will put out 96dB at 8W. You will find that pretty loud for a continuous tone. Typically an amp only gets anywhere near its maximum output on transients like drum hits, dynamic piano, etc.
-
Good to know that it would only really be using that much power on occasion.
-
An S3X at 2w sounds fine in nearfield with Paradigm Atoms and Overnight sensations in my Evil laboratory.
-
And not-so-near-field! (Yes, with a bit of help from subs.)
https://forum.bottlehead.com/index.php?topic=13966.msg127473#msg127473
-
Quick follow up question on testing what 8 watts sounds like.
If I run a 60Hz tone through my speakers and get the Volt meter to read 8V. If I stop the tone and switch to regular music will that represent how loud music will sound coming out of the Kaiju?
When I switched to music from the tone the volt meter dropped to 1V-2V when the music was playing.
-
That kind of depends on the settings on the device you're on and the music itself, so that's not a great comparison.
-
I suppose that makes sense. Is running a 60Hz signal going to take more power faster than music that focuses more on mids?
-
One more question.
I also found the Elekit TU-8900/8600 while looking for a Kit 300B. It seems to be similar to the Kaiju but I haven't been able to find any comparisons between the 2. Does anyone happen to know the differences between them?
Since I own the Mainline the headphone amp on the Elekit would be pretty useless.
-
That's a tough question to answer since it's a competitor's product, but I'll try to do my best to give some objective differences from my own perspective.
The Elekit in a way is more like what we used to sell back in the day. The kit is offered with some budget iron with lots of hints dropped that you should really go for the Lundahl upgrade if at all possible. We did this with our SEX monoblocks and Paramour monoblocks and we worked with Magnequest to create better iron for those pieces. There are some missing dimensions to the specs on those stock Elekit amps that I would imagine are rather drastically improved with the Lundahl bits.
The schematic for the 8600 is floating around and it has a vastly more complicated power supply than the Kaiju and active biasing circuitry, but the 300B driver is rather simple and multiple stages. I would expect less 120Hz noise making it from the power supply to the speaker terminals. The DC filament supply on this amp is a bridge rectifier and a cap.
The Kaiju has an incredibly simple power supply, very simple 300B biasing, but a more complicated driver stage, which is just a single triode driving the 300B. The increase in 120Hz noise that you might expect to see at the speaker terminals will be somewhat mitigated by the parallel feed output stage. The (available) DC filament supply is regulated and keeps Jac at EML happy.
I believe the 8600 with the Lundahl transformers will make more than 8W (maybe 11?), but it also runs pretty high plate voltage. R114/214 on the 8600 are twice the allowable value on the Western Electric published datasheet, and I have experienced this causing problems with Russian 300Bs in a different amplifier in the past, but YMMV and this is something I have run into in many 300B amps. With the 12AX7 input stage, the schematic shows either a 50K or 100K volume pot, and I would strongly advise against running a 100K pot into a 12AX7.
The Kaiju will make less power and requires a bias adjustment to the driver stage, so I would say it's less user friendly. I think the big advantage to the Kaiju comes if you happen to blow up one of the PC boards, as everything is modular and we can just send out replacement parts pretty easily. I've seen something like this happen from the wrong 9 pin tube being put into the amp, and a repair like that can be done pretty easily by the builder.
-
Music signals have peak voltages that can be 5 times the average, on well-recorded dynamic music. (Much pop music is severely compressed and the peak-to average ratio can be as low as 1.25 ). This is called "headroom." It complicates loudness prediction...
-
...and the Kaiju has some dynamic headroom above the 8W as well, particularly for short transients.
PJ and I can pretty much nuke any yes/no question asked on this forum ;)
-
PB has done a pretty good job of avoiding subjective comparisons with a competitive product, which has been our policy for the past 30 years. I'll just point out that the 11 watts output he's estimating for the Elekit vs. the 8 or 9 watts for a Kaiju means nearly jack when it comes to audible differences in power output. I'll also say that I feel very lucky having PJ around to design our iron. There are some very good winders out there and we went through most of the existing (and some no longer existing) winders over the years. We found that we could get closest to what we wanted - reasonable cost and very high performance - by PJ designing our own.
-
Thank you. That actually did answers quite a bit about the differences in parts.
I figures the Kaiju had higher quality transformers. I haven't read much on the quality of Lundahl transformers. I just know they are better than the cheap stock ones on the Elekit. I would get the DC filament on the Kaiju which, if I understood right, bring the noise level down to being on par with the Elekits more complex power supply.
Tube rolling and customizing is quite important to me and based on what you are saying the Kaiju is more accessible for modification. Also being able to use any 300B on the Kaiju is a huge plus.
11W vs 8W is maybe 10% more in volume difference. So really the power is negligible.
I didn't even think about how difficult repairs would be on the Elekit. Since it is all one board so if something goes wrong you would have to replace it all.
-
8W to 11W is 1.4dB, but both amps are going to clip pretty softly and have reasonable headroom.
-
I can’t speak for other people, but speaking for myself, I hate soldering and desoldering PC boards. The Elekit is one big PC board and my personal experience is that it’s really easy to mistakenly create solder bridges on PC boards. It’s also easier to create cold solder joints unless you’re experienced soldering PC boards. Desoldering PC boards is also a major PITA (although finally discovering solder suckers made it much easier). One of the many reasons I love Bottlehead kits is that they are largely NOT built on PC boards and are therefore much easier to solder, desolder, troubleshoot and modify.
Just my 2 cents and YMMV.
-
Since I am going to be using the Amp in a near field situation. Would the Stereomour II be a better amp to look at getting? I have read the 2a3 is a more musical sounding tube than the 300B. How does the sound differ between the Kaiju and the Stereomour II? Or would I need the extra power of the Kaiju for my speakers? If I understand correctly the Kaiju should net me an extra ~4db of sound.
-
In my opinion the 300B has a fuller sound with more weight to it then the slightly leaner more laid back sound of the 2A3.
I have a Kaiju which I use with a veriaty of speakers including some in the 85db range and I am happy with the sound...John
-
The iron in the Kaiju is also a bit better than the Stereomour, and the 5670 is the better sounding driver tube.
The Stereomour is possibly a bit easier to build because it is a bit simpler, but you also have to do all that input wiring to the selector switch which takes some extra time...
-
For tube rolling is there much variety in the 5670 tubes between brands? Or is the 300B more important for tube rolling?
-
They both make a difference, but I hear bigger differences between 300B tubes. Tube rolling with 300Bs gets expensive, however. But I found the expense of new production Western Electrics to be worth the upgrade in sonics and what I anticipate will be a longer life than the stock EH tubes.
It's pretty cheap to try different 5670s. My Kaiju kit came with GEs, and they sound pretty good. I've tried RCA, Sylvania, and vintage WEs, and none proved decisively better than the GEs. In fact, the WEs were a distinct disappointment.
-
The WE 300Bs may well be a sonic upgrade. But I wouldn't necessarily assume the EHs to be shorter on lifespan. I typically get six to ten years out of one.
-
Interesting. Thank you all for answering all my questions. I have just a couple more.
Is it possible to use 6SN7 tubes with adapters instead of the 5670 tubes? I only ask because I own 15 pairs of matched 6sn7 tubes.
Does the DC upgraded change the sound characteristics of the Kaiju?
Later on of I decide to upgrade the caps on the Kaiju. Which ones would be worth upgrading?
-
It would be possible to use 6SN7s in Kaiju, but you'd need more modifications than just an adapter. You'd also lose 6dB of gain.
The interstage coupling cap (0.1uF/630v) and parafeed output cap (10uF/630v)are the principal caps that are in the signal path. The shunt regulator stability Zobel cap (also 0.1uF/630v) also has has a minor effect on the sound, but it's on the regulator PC board and difficult to access.
These caps are subject to break-in changes, so allow at least 100 hours of music before critical listening.
-
A 6db loss seems like a lot. So probably not worth it to change to a 6SN7 tube input. How does upgrading the caps affect the sound? Should I wait to do the DC upgrade till I've put time on the amp?
-
Changing the caps will - subtly - change the sound. Whether it's an upgrade or a mistake is difficult to generalize; it depends too much on personal reaction. There is some consensus on the interwebs, but it changes often. I personally think the best benefit of cap rolling is that it educates your hearing, and you learn what you like. That's just my two cents though.
It's usually a good idea to build an amp stock first and run it for a few weeks. This gets it through break-in, educates your ear as to the baseline sound, and it helps catch a lot of small errors such as dirty tube pins, marginal solder joints, loose screws, etc. And it's much easier to debug any problems after a change when you know for sure it was working correctly before the change.
-
What varieties of the 5670 will work for the input socket on the Kaiju? I read in another post that some of the varieties aren't rated for high enough volts.
Will pretty much any of these tubes types work? I think this is full list of comparable tubes. 396A, GL5670, CK567, 2C51, 6CC42, 6Ð3П, 6N3P(EV, DR), 5670W, 5670WA, CK5670-WA, CV4013, GB-5670.
-
Do you have a link to the post about the varieties with insufficient voltage rating? (or which tube is not supposed to be adequately rated?)
-
Be aware that the maximum plate voltage rating of the 6n3p is 160v, whereas the 5670 is rated for 330v. In Kaiju, the regulator section runs at 300v, and the amplifier section at 175v. Use of the 6n3p will risk failure of the tube and collateral damage to other parts of the amp.
-
I'm not certain where PJ is finding that number, as the 6N3P shows 300V is acceptable for plate voltage:
https://frank.pocnet.net/sheets/113/6/6N3P.pdf (https://frank.pocnet.net/sheets/113/6/6N3P.pdf)
I've gone cross-eyed at times trying to keep Russian equivalent tube types straight in my head, so perhaps there's another tube that's maybe a letter off with that restriction, or there's a different grade that's derated, or even a conflicting datasheet out there!
-
I have edited that post today. If you read the posts that follow it, you'll get the full story. It's complicated.
Sorry for the confusion, I should have edited the post earlier.
-
So the E suffix ends up being the issue it seems, or perhaps the derated voltage is part of the trade for longer life?
-
Interesting.
-
Are there any input tubes that can be used with just an adapter or would anything besides the 5670 line be a sonic downgrade? Does the Kaiju require a pre-amp?
-
Kaiju was designed around the 5670, not with alternative tubes in mind. Most candidate drivers will need changes to the voltages and currents; some will also require an adapter. I looked at quite a number of candidates to pick the 5670, but have not done the detailed calculations for any alternatives, so I can't at this point say which might or might not be made to work out.
Sonic upgrades and downgrades are so much personal taste that I can't usefully comment.
Kaiju will usually need a preamp in most systems. There are exceptions, but not that many.
-
Thank you for the info. I take it the BeePre2 was designed to work in tandem with the Kaiju?
-
BeePre2 works well with lots of amps and, yes, it is the mate to the Kaiju.
-
BeePre2 works well with lots of amps and, yes, it is the mate to the Kaiju.
Thanks for the information. If I get the BeePre2 and the Kaiju would the 300Bs in both need to be matched? Would upgrading the tube on only 1 be waste?
-
Has anyone tried these tubes on either the Kaiju or the BeePre2? https://www.aliexpress.com/item/3256804189718927.html?spm=a2g0o.productlist.0.0.5dd43a53ypVCD6&algo_pvid=51ff7f37-7bc3-4439-856a-ab69f1a883a4&algo_exp_id=51ff7f37-7bc3-4439-856a-ab69f1a883a4-5&pdp_ext_f=%7B%22sku_id%22%3A%2212000028959587513%22%7D&pdp_npi=2%40dis%21USD%21800.8%21400.4%21%21%21%21%21%40210318cf16607231954034629e8ce0%2112000028959587513%21sea&curPageLogUid=yCZ6aMA01TJ1
-
If there's no datasheet for that tube, I would hold off on using it until they publish one.
-
<<If I get the BeePre2 and the Kaiju would the 300Bs in both need to be matched? Would upgrading the tube on only 1 be waste?>>
I have the beepre and a 300b BH amp. I think one pair of upgraded tubes is worth it. The nice thing is you can try them in both the amp and pre and see where you like them better.
-
If there's no datasheet for that tube, I would hold off on using it until they publish one.
I couldn't find a datasheet either. The most I can find is that it supports up to 16W output.
https://www.audionirvana.org/forum/the-audio-vault/electronics/149947-carbon-spray-new-changsha-shuguang-tube-52b-ta-on-behalf-of-300b-and-6300b
-
<<If I get the BeePre2 and the Kaiju would the 300Bs in both need to be matched? Would upgrading the tube on only 1 be waste?>>
I have the beepre and a 300b BH amp. I think one pair of upgraded tubes is worth it. The nice thing is you can try them in both the amp and pre and see where you like them better.
Thanks for the information.
-
A normal 300B can be made to give about 18W if desired. The plate structure looks like it could be larger, which might mean longer filament wires, and this leads to questions about how much current the filament draws.
If someone wants to take one for the team, a basic DC bench supply can be set to 5V and the alligator clip leads can be placed across the filament pins to see how much current it draws for heating. If the filament current is the same as a 300B, then you're likely good to go!
-
Do 6300B style tubes work? https://www.hifi-amplifiers.com/en/shuguang-electronic-tube-valve-c-68/shuguang-6300bta-vacuum-tubes-matched-pair-replace-300b98-2018-new-p-5252.html
-
I did get a sorta answer about the 52B.
"The technician from our manufacturer told us that 52B-TA can fully replace 300B Series Electron Tube.
Please don't worry.
The data sheet of 52B-TA also not available due to the relocation of the factory, it may need 6 more months to reopen the database."
-
The 6300 at least lists that the filament specifications are compatible with a normal 300B. This tube is likely to work fine in a BeePre or Kaiju, but it sure would be nice to get a set of plate curves out of them.
Do keep in mind that a tube like the 6300 won't make any extra power over a normal 300B without a different circuit, much like the JJ 2A3-40 in the Stereomour.
-
What is the normal range for filament current for a 300B? I see 300Bs with longer plates, like the TJ music 300B/C/+ is 2.4A. Is that drawing to much to work in the Kaiju?
https://www.eectech.store/fullmusic-300b-cne-innovative-version-of-the-tube-gold-feet-advanced-graphite-screen-p1003.html
Link with graphs.
http://www.mableaudio.com/en/productview.asp?sid=4045
-
Yes, 2.4A is about twice what a normal 300B requires, so that tube is very likely to cause major issues in most DC heated 300B amps. You also get no additional power out of a tube like that in a Kaiju.
-
This has been a problem since the early oughts when a certain European manufacturer created a hierarchy of tubes that didn't really plug into a 300B amp because of the filament current requirement or at least would not perform at their advertised maximum output in a 300B amp because of the amp circuit's designated operating point. They used a naming convention that implied they were an uprated 300B. A Chinese manufacturer started to emulate the tubes and used similar confusing names that had a "300" in them. The most extreme of these tubes can be good sounding and produce a fair amount more power, but need a whole 'nother amp to perform to their optimum.
-
Okay, so any 300B that is 2.4A is not actually a 300B. So, it seems like I need to double check any Chinese 300B to make sure it is actually 1.2A instead of 2.4A. I do see that there are a lot chinese tubes that say they replace 300B but are called 7300/6300/52/4300/30098 etc.
Or would the 2.4A work in the non-DC filament upgraded Kaiju?
-
Nope, the Kaiju has a small amount of series resistance between each heater winding on the power transformer and the 300B. If you double the voltage drop across these resistors, you'll be out of tolerance for the 300B filament. Even for 300B amps with the filaments connected directly to the power transformer secondary winding, you would need a 3A rated winding to properly heat that tube, and that's not always what's available!
You could modify a Kaiju to properly AC heat this tube, but then it will eat up normal 300Bs if you forget and plug them in. Again though, these tubes make no additional power in the Kaiju and are likely to have higher Miller capacitance, so I would not suggest using them.
-
well, I glad I asked before buying any Chinese tubes.
-
You can buy Chinese 300Bs. There are oodles of them that work just fine.
-
I'm going to buy some. Just didn't realize that there are ones labeled as 300B that wouldn't work in the Kaiju since they are 2.4A.
-
I finished the Kaiju and it works super well on my 87db speakers. I have the Kaiju hooked up to my Audio-GD Master-9 outs which uses a logarithmic volume control. I typically run the Master-9 at 28-33 out of 100 on the volume setting. So The Kaiju has plenty of power to work for low sensitivity near field speakers.
I can run the speakers to uncomfortably loud levels.
Though to get to a loud enough level to fill a large room the noise floor is to great for the speakers. So you end up with quite a bit of distortion.
Overall I'm very happy with the amp it sounds great and has lots of upgrade potential.
-
I typically run the Master-9 at 28-33 out of 100 on the volume setting. So The Kaiju has plenty of power to work for low sensitivity near field speakers.
The position of a volume control doesn't tell you much about what the amp is doing. You could put a Pass F4 in place of the Kaiju and you'd have to crank that volume control way up, but the F4 has 4x the power of the Kaiju.
I can run the speakers to uncomfortably loud levels.
Though to get to a loud enough level to fill a large room the noise floor is to great for the speakers. So you end up with quite a bit of distortion.
Noise that varies with the output level of your source is likely an issue that could be addressed on its own. If you have audible 60Hz hum from the Kaiju, the DC filament upgrade will address that.
-
That makes sense. I haven't installed the DC upgrade yet. Wanted to try the base kit for a while before upgrading.